Means mounting type slugs on toothed belt in chain printers

ABSTRACT

A chain printer containing a type chain which comprises a belt having a toothed side and which carries channel-shaped printing slugs along the print line. The web of each channel-shaped slug abuts the nontoothed side of the belt and has type characters thereon. The slugs&#39;&#39; flanges project across the edges of the belt and a pair of pins hold each slug at alternate teeth on the belt by extending between the flanges and projecting into holes therein. Each pair of pins abuts the opposite sides of a tooth and the adjacent side of the belt. A driving pulley moves the belt with a set of peripheral notches which mesh with those teeth not abutted by pins; a second set of peripheral notches is provided in the pulley for accommodating the abutting teeth and pins. When traveling around the pulley, the flanges pass over the pulley&#39;&#39;s sides and thereby guide the belt and slugs.

United States Patent [72] Inventors James H. Edwards Winchester; Alan M.Swett, Milton, both of Mass. [21] App1.No. 837,085 [22] Filed June 27,1969 [45] Patented Jan. 11, 1972 [73] Assignee Mohawk Data SciencesCorporation Herkimer, N.Y.

[54] MEANS MOUNTING TYPE SLUGS 0N TOOTl-IED BELT IN CHAIN PRINTERS 10Claims, 7 Drawing Figs.

[52] U.S.Cl 101/111 [51] Int. Cl B41jl/20, B4lj 1/30 [50] Field ofSearch 101/93 C, 93, 96,111,109, 383, 368

[56] References Cited UNITED STATES PATENTS 2,267,661 12/1941 Meyers101/111 2,936,704 5/1960 Hense 101/93 3,041,964 7/1962 Simpson et al101/111 3,041,965 7/1962 Sasaki 101/111 3,142,249 7/1964 Sasaki 101/111Primary Examiner-William B. Penn Attorneys- Francis J. Thomas, RichardH. Smith, Thomas C. Siekman and Sughrue, Rothwell, Mion, Zinn andMacpeak ABSTRACT: A chain printer containing a type chain whichcomprises a belt having a toothed side and which carries channel-shapedprinting slugs along the print line. The web of each channel-shaped slugabuts the nontoothed side of the belt and has type characters thereon.The slugs flanges project across the edges of the belt and a pair ofpins hold each slug at alternate teeth on the belt by extending betweenthe flanges and projecting into holes therein. Each pair of pins abutsthe opposite sides ofa tooth and the adjacent side ofthe belt. A drivingpulley moves the belt with a set of peripheral notches which mesh withthose teeth not abutted by pins; a second set of peripheral notches isprovided in the pulley for accommodating the abutting teeth and pins.When traveling around the pulley, the flanges pass over the pulleyssides and thereby guide the belt and slugs.

PATENTED JAN] 1 I972 3533500 saw 1 OF 4 INVENTORS JAMES H. EDWARDS ALANM. SWETT ATTORNEY PATENTED JAN] 1 1972 31633500 SHEET 3 BF 4 PATENTEUJAN] 1 I972 SHEET 4 UF 4 MEANS MOUNTING TYPE SLUGS ON TOOTHED BELT INCHAIN PRINTERS BACKGROUND OF THE INVENTION This invention relates tochain printers and, more particularly, to a type chain in such a printerand to the means used to move and guide the type chain.

Printers have been developed in which a type chain comprising typecharacters on a chain of printing slugs secured to a belt is moved alonga print line across the document. In these printers, commonly calledchain printers, one or more hammers adjacent the print line selectivelystrike a document against the moving type characters.

However, problems peculiar to chain printers have been encountered. Theslugs must be positioned on the belt at precise locations and a suitableway of securely fastening the slugs onto the belt is required.

Another problem is found in guiding the moving chain with the necessaryaccuracy to enable the hammers to precisely strike the type character atthe proper time. Without such precise hammer impact, poor registrationof the type characters on the paper will occur. Mechanical and magneticdevices have been used. However, these devices, by contacting the slugsor belt, generate undesirable noise and friction. In some caseslubrication even is required.

In some chain printers, replacement of an individual printing slugrequires the removal of a large number of slugs from the belt and is atime-consuming job. Difi'iculties have been encountered in developingprinting slugs which may be easily removed from the belt forreplacement, yet remain securely fastened during printing operations.

SUMMARY OF THE INVENTION It is, therefore, the primary object of thisinvention to provide a chain printer in which the above problems areovercome and yet is economical to manufacture and maintain.

In accordance with the invention, there is provided a chain printerhaving a type chain comprising a plurality of printing slugs, each ofwhich has a printing portion and upper and lower portions cantileveredfrom the printing portion. These slugs are secured to a movable belthaving a toothed side. The printing portion of each slug abuts anontoothed side of the belt and its upper and lower portions projectacross the belt's edges. At least one pin, extending between the upperand lower portions of each slug, securely fasten each slug to the belt.Preferably, a pair of pins abuts the opposite sides of a tooth at whichthe slug is located and the adjacent side of the belt. By simplyremoving the necessary pins the slugs may be individually and easilyreplaced.

The belt is driven by a driving pulley having two sets of peripheralnotches. One set meshes with at least some of the belts teeth and drivesthe belt. The other set accommodates the pins and, in the preferredembodiment, also those teeth abutting the pins as the belt travelsaround the pulley. When moving around the pulley the upper and lowerportions of the slugs pass over the sides of the pulley and effectivelyguide the type chain.

Additionally, a member is placed adjacent the print line to resist theimpact of the hammers as they force the slugs and document together.Another member stops the slugs upon their rebound from the impactresisting member. However, except when performing their respectivefunctions, neither of these members contact the moving belt or slugs.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a schematic perspective viewof a preferred embodiment of the printer.

FIGS. 2 and 3 are perspective views of a printing slug attached to thebelt.

FIG. 4 is a perspective view of a pin used to secure the slugs onto thebelt.

FIG. 5 is a plan view, partly in section, showing the driving pulleymoving the print chain.

FIG. 6 and 7 are sections taken along lines 66 and 7--7 in FIG. 5respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 schematically shows achain printer printing on a document I which bends around guide bars 2while being moved upwardly by a pair of tractors 3 engaging edgeperforations la in the paper. The printer includes a plurality of hammermechanisms disposed along the print line, i.e., that line along whichcharacters are being printed. Each hammer mechanism contains a hammer 4awhich, when activated by an electromagnet 4b, moves about its pivot 4c.One or more fonts of type characters are moved along the print lineadjacent the hammers 4a by a type chain moving at a constant speed in afixed revolving path. The type chain comprises a plurality of printingslugs '5 on which the type characters are located and an endlessflexible belt 6, (FIG. 5) on which the slugs 5 are secured. During aprinting operation, the proper hammer mechanisms are activated so thattheir hammers impact an inked ribbon 7 and the document 1 againstselected type characters on the slugs 5. The inked ribbon is locatedbetween the document 1 and the type chain and is fed from a supply spoolonto a takeup spool 8b.

The type chain is moved around a pair of pulleys: an idler pulley 9a,and a driving pulley 9 which is driven by means not shown located withina printer support 10. A conventional code disk 12 is mounted on theshaft 13 of the idler pulley 9a. It contains a plurality of radial slotswhich represent the rotating type characters and a further slot forindicating the end of each font. Light from a light source 15 isdirected onto the code disk and passes through the slots therein andonto a photosensitive unit 14. By this well-known arrangement, thephotosensing unit produces electrical outputs representing the positionsof the type characters in the moving type chain. Such electrical signalsare then used to properly time the activation of the hammer mechanisms.

As shown in FIGS. 2 and 3, the belt 6 of the type chain has a toothedside 6a on which a plurality of equally spaced teeth 16 are located. Thebelt is formed from fiberglass-reinforced neoprene and is of a typecurrently manufactured by the US. Rubber Company as a timing belt. Thenontoothed smooth side 6b of the belt is abutted by the printingportions 17 of the slugs 5. Each slug 5 is channel shaped with theprinting portion being the channels web and having one or more typecharacters 18 thereon. Four raised type characters are located on theslug illustrated. By using a plurality of type characters on each slugthe printing speed may be increased with respect to the revolving speedof the type chain. The type characters are located equidistant from thetop and bottom of the slugs, so

that the hammers do not tend to overturn the slugs when providing impactbetween the type characters and document. The flanges of thechannel-shaped slugs,.their upper 19 and lower 20 portions, arecantilevered from the printing portions 17 of the slugs and projectacross the belts edges. If desired, the upper 19 and lower 20 portionscan have slots therein to accommodate the belt where they project overthe belts sides. The upper and lower portions each have a ledge, 21 and22, at their cantilevered ends, i.e., their ends furthest away from theprinting portion 17. Each ledge and the upper or lower portion on whichit is located has a pair of holes 23. Extending between the upper andlower portions and projecting into the holes 23 therein are a pair ofpins 24.

As shown in FIG. 4, the pins are elongated coil springs commonly calledSpirol Pins. When installed, each pin is wound upon itself and itsdiameter thuscompressed, placed in the holes 23 and thereafter allowedto.expand. The pins abut both the opposite sides of a tooth I6 and theadjacent side of the belt 60 on which the teeth 16 are placed. Solocated, each pair of pins securely fasten a slug to the belt, yet bycompressing and removing the pins, the slugs may be easily removed fromthe belt. In addition, each slug may be individually removed from thebelt by merely taking out the pair of pins which secure it thereto.

F IG. 5 illustrates the method in which the belt is driven by thedriving pulley 9. The pulley has two differently sized sets ofperipheral notches 30 and 31. A pulley of this configuration may beeasily constructed from a gear having equally spaced peripheral teeth bymerely removing every third tooth. The printing slugs S are located atalternate teeth on the belt 6. Those teeth not abuted by a pair of pins24 mesh with the notches 31 in the pulley formed by adjacent gear teeth.Those notches 30 of the pulley formed by removing one of the gears teethaccommodate the abutting pins and teeth. Thus, the belt is accuratelydriven by the pulley via one set of the pulley s notches and those teethnot abutted by pins. Of course, the idler pulley 90 around which thetype chain also travels has two similar sets of notches to accommodatethe teeth 16 and pins 24.

The cantilevered ends of the upper and lower portions, 19 and 20, of theprinting slugs 5 have their corners removed so that the cantileveredends of the upper and lower portions are smaller than their endsadjacent the printing portions 17 of the slugs. Since these ends areclosest to the centers of the driving and idler pulleys when the typechain moves around them, movement of the slugs around the pulleys isfacilitated. Removal of the slugs corners also has the desirable effectof concentrating the mass of each slug toward its center and thusenhances the stability of the slugs.

As shown in FIGS. 5 and 6, when the slugs 5 travel around the drivingpulley 9 their upper and lower portions 19 and 20 pass over the pulleyssides. Similarly, at the other end of the type chain they travel overthe sides of the idler pulley 90. With sufficient tension maintained inthe belt, the upper and lower portions sufficiently guide the entiretype chain in this manner.

FIGS. 1, 5 and 7 show an impact resisting member disposed between thepulleys 9 and 9b and between the type chain. It is an essentially fiatmember having concave ends which adjoin the driving and idler pulleys.The impact resisting member is located adjacent the print line andprovides the backstop neces ary to resist the impact from the force ofthe hammers 4a as they force the document against the inked ribbon andtype characters 18 on the slugs. By rebounding from the slugs and theimpact resisting member, the hammers return to their initial positions.When a hammer is operated to strike a type character on a slug, thatslugs upper and lower portions are forced against the impact resistingmember. How ever, when they are not being forced together, a slightclearance is provided between the impact resisting member and meprinting slugs. The slugs do not contact or ride along the impactresisting member and noise and friction is avoided.

FIGS. 5 and 7 also show a stop member 26 secured adjacent the print lineto the impact resisting member 25 with screws 27. The stop member 26 hasa lip 28 extending parallel to the print line and placed adjacent thoseends of the ledges 21 disposed away from the cantilevered ends of theupper portions of the slugs. With this arrangement the stop member 26prohibits the printing slugs from rebounding an unsatisfactory distanceaway from the impact resisting member 25 after the slugs are impacted bythe hammers. As with the impacting resisting member, clearance isprovided between the stop member 26 and the slugs 5, thus avoiding noiseand friction. The ledges, 2 and 22 on the upper and lower portions ofthe slugs have an additional function; they provide an enlarged bearingsurface between the slugs and the impact resisting member 25 whenoperation of the hammers force the two together.

Even though the slugs 5 do not ride on the impact resisting member 25,impact between these member during the printing operation causes wear.To minimize such wear, the slugs are preferably made of beryllium copperand the impact resisting member of hard-coated aluminum. Dispersion of alubricative material, such as Teflon, in the hard coating is alsopreferred. Such materials provide the desired hardness and lubricationbetween the members. However, the slugs may also be made of hardenedsteel of metal-coated plastic and the impact resisting member ofchrome-plated steel.

in summary, the print chain is effectively guided by the upper and lowerportions, 1? and 20, of the slugs 5 as they pass over the sides of thedriving and idler pulleys, 9 and 9a. Each slug 5 may be easily andindividually removed from the belt 6 by removing a pair of pins 24,although each pair of pins abutting both the opposite sides of a toothl6 and the belt itself securely fasten each slug to the belt. Noise andfriction is avoided by clearances between the slugs 5 and the impactingresisting member 25 and the stop member 26.

We claim:

1, A type chain assembly comprising:

a. a movable flexible belt having first and second sides;

b. a plurality of spaced teeth located on the first side of the belt;

c. a plurality of printing slugs, each slug having a printing portionwith at least one type character thereon abutting the second side of thebelt, each slug also having at least one portion cantilevered from theprinting portion and projecting across an edge of the belt;

d. at least one member securing each slug to the belt, the

securing members extending from the cantilevered portions of the slugs,positioned on the first side of the belt and located at some of theteeth; and

e. a driving pulley for moving the belt, the pulley having at least twosets of peripheral notches, one set adapted to mesh with some of theteeth, another set adapted to accommodate the securing members and theteeth at which they are located when the belt moves over the pulley.

2. The type chain assembly as recited in claim 1 wherein a pair ofsecuring members extend from the cantilevered portion of each slug, eachpair of members abutting opposite sides of a tooth on the first side ofthe belt.

3. The type chain assembly as recited in claim 2 wherein the notches inthe pulley in the two sets are alternately arranged, alternate teeth onthe belt are abutted by the securing members and the teeth on the beltare uniformly spaced.

4. The type chain assembly as recited in claim 2 wherein each pair ofsecuring members also abuts the first side of the belt.

5. The type chain assembly as recited in claim 2 wherein each slug hastwo cantilevered portions which project across opposite edges of thebelt and the securing members comprise pins projecting from the slugscantilevered portions.

6. The type chain assembly as recited in claim 5 wherein each of thecantilevered portions of each slug contains a pair of holes and eachsecuring member is a pin extending between the two cantilevered portionsof a slug and projecting into a hole in each portion.

7. The type chain assembly as recited in claim 2 wherein at least partof the cantilevered portions of the slugs are adapted to pass over thesides of the driving pulley when the belt travels over the pulley.

8. A type chain assembly comprising:

a. a movable belt having first and second sides;

b. a plurality of spaced teeth located on the first side of the belt;

. a plurality of printing slugs, each slug having a printing portionwith at least one type character therein abutting the second side of thebelt, each slug also having at least one portion cantilevered from theprinting portion and projecting across an edge of the belt;

d. at least two pins securing each slug to the belt, the pins extendingfrom the slugs cantilevered portion, positioned on the first side of thebelt, and abutting opposite sides of a tooth; and

e. a driving pulley for moving the belt, the pulley having at least twosets of peripheral notches, one set adapted to mesh with some of theteeth, another set adapted to accommodate the pins and the teeth theyabut when the belt moves over the pulley.

9. The type chain assembly as recited in claim 8 wherein each pair ofpins also abut the first side of the belt.

10. The type chain assembly as recited in claim 8 wherein each slug hastwo cantilevered portions which project across opposite edges of thebelt, each of the two cantilevered portions contains a pair of holes,and each pin extends between the two cantilevered portions of a slug andprojects into a hole 5 in each portion.

1. A type chain assembly comprising: a. a movable flexible belt havingfirst and second sides; b. a plurality of spaced teeth located on thefirst side of the belt; c. a plurality of printing slugs, each slughaving a printing portion with at least one type character thereonabutting the second side of the belt, each slug also having at least oneportion cantilevered from the printing portion and projecting across anedge of the belt; d. at least one member securing each slug to the belt,the securing members extending from the cantilevered portions of theslugs, positioned on the first side of the belt and located at some ofthe teeth; and e. a driving pulley for moving the belt, the pulleyhaving at least two sets of peripheral notches, one set adapted to meshwith some of the teeth, another set adapted to accommodate the securingmembers and the teeth at which they are located when the belt moves overthe pulley.
 2. The type chain assembly as recited in claim 1 wherein apair of securing members extend from the cantilevered portion of eachslug, each pair of members abutting opposite sides of a tooth on thefirst side of the belt.
 3. The type chain assembly as recited in claim 2wherein the notcHes in the pulley in the two sets are alternatelyarranged, alternate teeth on the belt are abutted by the securingmembers and the teeth on the belt are uniformly spaced.
 4. The typechain assembly as recited in claim 2 wherein each pair of securingmembers also abuts the first side of the belt.
 5. The type chainassembly as recited in claim 2 wherein each slug has two cantileveredportions which project across opposite edges of the belt and thesecuring members comprise pins projecting from the slugs'' cantileveredportions.
 6. The type chain assembly as recited in claim 5 wherein eachof the cantilevered portions of each slug contains a pair of holes andeach securing member is a pin extending between the two cantileveredportions of a slug and projecting into a hole in each portion.
 7. Thetype chain assembly as recited in claim 2 wherein at least part of thecantilevered portions of the slugs are adapted to pass over the sides ofthe driving pulley when the belt travels over the pulley.
 8. A typechain assembly comprising: a. a movable belt having first and secondsides; b. a plurality of spaced teeth located on the first side of thebelt; c. a plurality of printing slugs, each slug having a printingportion with at least one type character therein abutting the secondside of the belt, each slug also having at least one portioncantilevered from the printing portion and projecting across an edge ofthe belt; d. at least two pins securing each slug to the belt, the pinsextending from the slug''s cantilevered portion, positioned on the firstside of the belt, and abutting opposite sides of a tooth; and e. adriving pulley for moving the belt, the pulley having at least two setsof peripheral notches, one set adapted to mesh with some of the teeth,another set adapted to accommodate the pins and the teeth they abut whenthe belt moves over the pulley.
 9. The type chain assembly as recited inclaim 8 wherein each pair of pins also abut the first side of the belt.10. The type chain assembly as recited in claim 8 wherein each slug hastwo cantilevered portions which project across opposite edges of thebelt, each of the two cantilevered portions contains a pair of holes,and each pin extends between the two cantilevered portions of a slug andprojects into a hole in each portion.